Glucose 6 Phosphate Dehydrogenase (G6PD Quantitative)

The glucose‑6‑phosphate dehydrogenase (G6PD) quantitative test measures enzyme activity in red blood cells to diagnose and grade G6PD deficiency. It reports an exact activity level (often adjusted for hemoglobin), helping predict hemolysis risk, guide safe medication choices, support newborn screening, and evaluate unexplained anemia or jaundice. Results classify activity as normal, intermediate, or deficient.

A high G6PD result usually doesn’t indicate deficiency. It can reflect recent hemolysis with many young red cells (reticulocytosis), a recent blood transfusion, laboratory variability, or a benign high-normal variant. Because hemolysis or transfusion can falsely raise measured activity, repeat testing when clinically stable and discussion with your clinician are recommended to clarify the significance.

G6PD testing can be either qualitative or quantitative. Qualitative screening tests identify deficiency (yes/no) but may miss intermediate activity, especially in heterozygous females. Quantitative assays measure enzyme activity (units per gram hemoglobin or per RBC) to determine severity and guide management. Results should be interpreted with clinical context and, when necessary, repeat testing after hemolytic episodes.

If you have G6PD deficiency you’re often asymptomatic until oxidative stress triggers red‑cell breakdown. You may develop acute hemolytic anemia — sudden fatigue, pale skin, rapid heartbeat, shortness of breath, jaundice and dark urine. Newborns can get severe jaundice. Infections, certain drugs (e.g., primaquine, some sulfa drugs, dapsone, nitrofurantoin), fava beans and chemicals can provoke attacks. Management is avoidance and supportive care.

People with G6PD deficiency should avoid fava (broad) beans and products containing them — these are classic triggers of hemolysis. Also steer clear of herbal remedies, supplements or foods known to contain strong oxidants (some traditional/herbal preparations and certain additives), and avoid accidental ingestion of naphthalene from contaminated storage. Always check with your doctor or pharmacist before trying new supplements or unfamiliar foods.

No. G6PD deficiency is a genetic X‑linked enzymatic disorder, not an autoimmune disease. It stems from reduced glucose‑6‑phosphate dehydrogenase activity in red blood cells, making them vulnerable to oxidative stress (certain drugs, infections, fava beans) and causing episodic hemolysis. The immune system does not attack red cells; management centers on avoiding triggers and treating hemolytic episodes.